The effects of B. subtilis on the morphology and physiology of saffron were investigated using two types of soils. Three different bacterial suspensions were applied at 14-day intervals to treat saffron. Morphological attributes were recorded, and the amounts of α-crocin and safranal in the stigma extracts were quantified. The longest stigma, petal, and leaf were observed in the treated groups with 105 and 108 cfu/ml. The highest weight of stigma per corm belonged to the treated groups with 102 cfu/ml in unsterile soil and 105 and 108 cfu/ml in sterile soil. Treatment with 102 and 108 cfu/ml caused a significant increase in safranal production in sterile and unsterile peat/perlite. While treatment with 105 and 108 cfu/ml in sterile peat/perlite and exposure to 102 cfu/ml in unsterile peat/perlite soil resulted in an increase in α-crocin. The data showed that B. subtlis triggers the morphological and physiological processes in saffron.
Keywords: Bacillus subtilis; saffron; safranal; α-crocin.